# 数组乘积方法
def Cheng(ssr):
    j = 1
    for x in ssr:
        j = j * x
    return j


# 乘积数组
li = []
# 循环添加
while True:
    # 临时循环数组
    li1 = []
    for i in range(1,21):
        # 临时循环数组
        li1.append(i)
        li.append(Cheng(li1))
    break
print(sum(li))


